Résumé
In this dissertation, I examine the scientific, ethical and political bases on which the protection of biodiversity can be grounded. In the first part, I study the scientific resources available to understand and protect biodiversity. After a description of the historical context in which the concern for biodiversity appeared, I describe the level of generality and the predictive power of conservation biology. I then show that this discipline needs to enter into dialogue with the social sciences if it is to fulfill its mission. Finally, I specify how biodiversity must be understood, proposing to add to its traditional definition the potential for diversification, and rejecting the attempt to reduce biodiversity to wilderness. In the second part, I examine the value of biodiversity and the moral principles that can justify its protection. I first consider its value for human beings. I then suggest widening the sphere of our moral considerations to all living beings. Finally, I defend the attribution of a non-instrumental value to biodiversity itself, considered as the process of biological diversification. In the third part, I analyse two political issues at stake in the protection of biodiversity: the Convention on Biological Diversity (CBD), and the norms of sustainable development. Analysing the CBD in light of the debate between realism and cosmopolitanism in the philosophy of international relations, I show that these two approaches, while theoretically opposed, can converge in practice when one distinguishes the (resolutely realist) process of negotiation from its result (which can be interpreted in a cosmopolitan framework). I then criticize the growing influence of the norms of sustainable development which lead us to consider environmental problems strictly in terms of inter-generational equity. This strongly anthropocentrist approach prevents us from asking relevant questions and from identifying the real causes of the present crisis insofar as it impedes us from critically examining our relationship to the natural world. In my conclusion, I propose some theoretical avenues that would allow us to elaborate a policy of protection of biodiversity which would reconcile the respect of people and the non-instrumental valuation of the natural world. Keywords. philosophy; philosophy of science; ethics; justice; environment, conservation biology; intrinsic value; anthropocentrism; biocentrism; cosmopolitanism.